on adhesive surfaces ~2.8×10^8: on non-adhesive surfaces ~1×10^8 Pa×s/m
||Zebrafish Danio rerio
||Ruprecht V et al., Cortical contractility triggers a stochastic switch to fast amoeboid cell motility. Cell. 2015 Feb 12 160(4):673-85. doi: 10.1016/j.cell.2015.01.008. p.681 left column bottom line & right column top linePubMed ID25679761
||P.681 left column bottom paragraph:"To understand this efficient and persistent motile behavior, [investigators] asked how stable-bleb cells move in 2D confined environments. Depletion of cortical elements in the cell front (Figure 4A) and the diffuse zone of actin net polymerization in the spherical front (Figure 4D), exclude a classical polymerization-driven locomotion strategy, where polymerizing actin filaments push the leading edge plasma membrane forward. However, the presence of fast retrograde cortical flows led [them] to hypothesize that coupling of the flowing actin network to the surrounding substrate powers stable-bleb cell migration under 2D confinement. To test this hypothesis, [they] performed high-resolution live cell imaging of retrograde cortical flows in stable-bleb cells in confinement under agarose. Motile stable-bleb cells on adhesive Fibronectin-coated substrates showed a rapid decay of flow velocities toward the cell rear with a pronounced zone of zero flow speed (Figures 6A–6F and 6H Movie S5). In contrast, non-motile stable-bleb cells that were placed on passivated PEG-coated substrates revealed considerably different retrograde flow profiles with similar maximal flow velocities to motile cells in the cell front, but a slower decay of flow speeds to the cell rear (Figures 6G and S3D)."
||P.681 left column bottom paragraph: "Using a 1D fluid description of the cortex, [investigators] estimated from those cortical flow profiles a higher frictional coefficient ξ on adhesive in comparison to non-adhesive surfaces (ξadhesive ≃ 2.8 × 10^8 Pa × s/m versus ξnon-adhesive ≃ 1 × 10^8 Pa × s/m Figures S4A–S4C)." Supplementary information p.8 table S1:"ξ=friction coefficient between actin filaments and bulk cytoplasm and/or ECM"